1. Technical Field
The present invention relates to a stator core of a dynamoelectric machine.
2. Description of the Related Art
Generators are found in virtually every motor vehicle manufactured today. These generators, also referred to as alternators, produce electricity necessary to power a vehicle""s electrical accessories and charge a vehicle""s battery. Generators must produce electricity in sufficient quantities to power a vehicle""s electrical system. Furthermore, generators must produce electricity having the characteristics necessary to be compatible with a vehicle""s electrical components. A generator typically includes a stator assembly comprising a stator core and a stator winding, and a rotor.
U.S. Pat. No. 3,953,753 issued to Barrett entitled xe2x80x9cTHREE PHASE ALTERNATORSxe2x80x9d disclose a three phase alternator suited for automotive use having an annular magnetic stator core having a plurality of stator poles projecting therefrom, and separated from each other by a corresponding plurality of stator slots. Each slot has an open bottom formed by tooth tips of adjacent stator teeth. The slot opening is relatively narrow, compared with a width of the slot itself, as is conventional, so as to provide both a magnetic flux path and provide for wire retention. However, the relatively narrow slot opening formed by the tooth tips, which are typically stamped directly into a steel lamination into the desired profile, restricts entry of the stator windings. Accordingly, obtaining an increasingly higher stator slot fill (i.e., the percentage of copper wire total cross-sectional area to available cross-sectional area) is difficult to achieve.
There is therefore a need to provide a stator core for a dynamoelectric machine that minimizes or eliminates one or more of the problems set forth above.
One object of the present invention is to provide a stator core for a dynamoelectric machine such as an alternating current (AC) generator that solves one or more of the problems set forth above. The present invention provides a slot opening that is increased relative to conventional slot openings (i.e., when compared to the width of the slot itself). The increased size slot openings allow stator windings to be more easily inserted into the slots, and further, provides for an increased slot fill. Thereafter, the slot opening is closed up in order to provide a magnetic flux path and further to provide for wire retention. This is accomplished by cold-forming the ends of the stator teeth after the core itself has been made and wound with the stator winding to form xe2x80x9ctooth tips.xe2x80x9d
In accordance with the present invention, a stator assembly for a dynamoelectric machine is provided, and which includes a stator core having a yoke, a plurality of teeth separated by intervening slots. The stator core extends along a longitudinal axis. A radially innermost portion of at least one of the teeth includes a pair of legs with a recess located therebetween. The arrangement of the legs and the recess facilitates the cold-working of the stator teeth to form the tooth tips.
A method of making a stator assembly according to the invention is also presented.
Other features and advantages will be apparent to those of ordinary skill in the art from the detailed description and accompanying drawings describing and illustrating the invention by way of example only and not by way of limitation.